Computer assisted radiation therapy machine

ABSTRACT

A computer assisted radiation therapy machine is disclosed. The machine includes a rotatable gantry having a radiation source portion which is rotatable about a patient treatment couch. Geometric and dose parameters of the machine for defining a prescribed treatment plan of radiation are stored in the memory of the computer. A readout and display means is provided for displaying the geometric and dose parameters of the defined radiation treatment plan. Editing and updating capability are provided for editing and updating the treatment plan with the cumulative radiation dose administered to each portal and the total cumulative dose administered to the patient. Each parameter of a proposed treatment plan is compared with permissible ranges of machine parameters stored in a memory to verify that the proposed treatment is within the permissible range of the machine.

United States Patent 1191 Pavkovich COMPUTER ASSISTED RADIATION THERAPYMACHINE [75] Inventor: John M. Pavkovich, Palo Alto, Calif.

[73] Assignee: Varian Associates, Palo Alto, Calif.

[22] Filed: Nov. 27, 1970 [2]] Appl. No.: 93,331

[52] US. Cl 235/151, 250/615, 444/1 [51] Int. Cl A6ln 5/01 [58] Field ofSearch 235/l5l, 61.6 H,

. 1451 Jan. 1, 1974 Primary ExaminerEugene G. Botz Attorney-Stanley Z.Cole and Leon F. Herbert 5 7 ABSTRACT A computer assisted radiationtherapy machine is disclosed. The machine includes a rotatable gantryhaving a radiation source portion which is rotatable about a patienttreatment couch. Geometric and dose parameters of the machine fordefining a prescribed treatment plan of radiation are stored in thememory of the computer. A readout and display means is provided fordisplaying the geometric and dose parameters of the defined radiationtreatment plan. Editing and updating capability are provided for editingand I Refelfllces Cited updating the treatment plan with the cumulativeradia- UNITED STATES PATENTS tion dose administered to each portal andthe total cu- 3,591,806 7 1971 Brill er al. 250/615 x mulative doseadministered to the Patient Each P 2 943 205 9 0 Kazan et 1 250 95 UXrameter of a proposed treatment plan is compared 3,100,843 8/1963 Foster250/95 X with permissible ranges of machine parameters stored in amemory to erify the proposed treatment IS within the permissible rangeof the machine. 831,597 l/l970 Canada 235/l5l I 9 Claims, 4 DrawinglFigures DIGITAL CASSETTE TAPE UNIT 28 Z B E J M E M 0 R Y CEN T RA L iP R0 C E SSDR ANALDG/ DIGITAL C 0 N V E RTE RS DIGITAL T0 ANALOG CON VERT E R5 SE N SONS i1 CONTROL LINES II AC H I N E I N T E R FACE L:

- '11111111111111 Ionsunou SAFETY 46 1115111001 RELAY +v PATENTEO JAR II974 SHEET 1 OF 3 MACHINE CONSOLE CENTRAL PROCESSOR ANALOG/DIGITALCONVERTERS SENSORS A CONTROL LINES MACHINE INTERFACE DIGITAL CASSETTETAPE UNIT 28 {RADIATION ION BUTTON SAFETII 46 INTERLOCK RELAY 45 2INVENTOR JOHN H. PAVKOVICH ATTORNEY PATENTEDJAH H974 3.783.251 sum 2 ora @ART T READ IN PATIENT RECORD READY SET CONSOLE READY WRITE OUTPATIENT RECORD ENABLE BEAM FIG.3A

PATENTED JAN 1 i974 SHEET 30$ 3 YES RRENT CLINAC N z 0 TOTO TREATMENTDATA BUFFER TRANSFER CU DATA INCLUDI WEDGE RAD/D nom S E I DISABLE BEAMDISABLE BEAM FIG.3B

COMPUTER ASSISTED RADIATION THERAPY MACHINE DESCRIPTION OF THE PRIOR ARTHeretofore, the mechanical setup of a radiation therapy machine has beenautomated for decreasing the setup time and improving the accuracy ofthe mechanical setup for a radiation therapy treatment. In the priormachine, the desired positional information for the mechanical setup ofthe machine was punched into cards according to a prescribed plan oftreatment. A deck of cards representing the setup for the prescribedplan of treatment was fed into a card reader. The output of the cardreader was fed to control circuits for sequentially controlling themechanical motion of the various movable parts of the machine forgeometrically positioning the machine according to the prescribed planof treatment. A four digit visual display was provided for displayingthe position of each of the mechanically movable elements of theradiation therapy machine.

While the aforecited automated radiation therapy machine substantiallydecreased the setup time and improved the accuracy of the setup, it didnot include means for automatically maintaining an updated read ing ofcumulative radiation dose delivered to a patient through a prescribedradiation portal nor did it automatically maintain a cumulative total ofradiation administered to a given patient.

The prescribed treatment plan for a patient, in the prior machine, couldbe edited and updated by punching a new set of punched cards. However,mistakes could be made by the keypunch operator and these mistakes wouldbe incorporated into the treatment plan to be administered to thepatient.

It is desired to obtain an improved automated radiation therapy machinewhich automatically verifies a proposed plan of treatment against arange of permissible values to prevent setting up or editing a treatmentplan which is not in conformance with a predetermined range ofpermissible values for each parameter of a treatment plan.

SUMMARY OF THE PRESENT INVENTION The principal object of the presentinvention is the provision of an improved automated radiation therapymachine. V s

One feature of the present invention is the provision of means forautomatically editing and updating a patients treatment plan with thecumulative total of radiation dose, if any, administered to the certainpatient.

Another feature of the present invention is the same as the precedingfeaturewherein the means for automatically editing and updating thepatients treatment plan includes a programmed general purpose computer.

In another feature of the present invention, cathode ray tube keyboardterminal or a teletype terminal is interactively coupled to a generalpurpose computer for editing, reading out, and displaying the updatedtreat ment plan. I

In another feature of the present invention, information defining aradiation treatment plan for a given patient is stored in a first memorymeans, such as a magnetic tape cassette paper tape or magnetic disc.This information is transferred into the memory of the computer and thecomputer reads the stored information, upon command, to a readout anddisplay terminal having the capability for updating the treatment planinformation stored in the computer.

In another feature of the present invention, information is storeddefining permissible ranges of values for a treatment plan of machineparameters and the corresponding parameters of a proposed treatment planare compared against the stored range of permissible values to derive aninterlock output if the value of a proposed machine parameter is outsidethe range of permissible values to derive an interlock output if thevalue of a proposed machine parameter is outside the range ofpermissible values. The interlock output is employed to prevent transferof the proposed treatment parameter into the treatment plan for thepatient.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERREDEMBODIMENTS Referring now to FIG. I, there is shown a computercontrolled radiation therapy machine incorporating features of thepresent invention. The radiation machine such as a CLINAC radiationtherapy machine model 4 or 35, commercially available from VarianAssociates, or a TljERATRON automatedgobalt 60 radiation machine made byAtomic Energy of Canada Limited of Ottawa, Canada, includes a couch 2having a table portion 3 which receives the patient to be treated. Thecouch 2 is rotatable about a vertical axis 4 by means of a turntable 5which the couch 2 is affixed. The couch includes an elevator portion 6for translating the couch in the vertical direction Z. In addition, thecouch includes motorized drives for translating the table 3 in thelateral Y direction and longitudinal X direction. A control pendant 10is connected to the couch 2 via suitable cable for manual control of thevarious portions of the radiation machine I and for allowing automaticcontrol of the radiation machine 1 by the computer.

A generally C-shaped gantry 8 is rotatable by 359 about a horizontal ads9. The gantry 8 is rotatably sup ported from a stand 11. A source ofradiation, such as a linear accelerator producing a high energy electronbeam which is directed against an X-ray target, produces a beam ofX-rays emanating from a collimator head portion 12. As an alternative,in the case of the cobalt machine, the cobalt serves as a source ofX-ray radiation, and is housed within the collimator head portion 12.The X-rays are directed out of the radiating head portion 12 in a beamhaving; an axis l3'which intersects the gantry axis of rotation 9 at aposition identified as the isocenter 14, which is also intersected bythe turntable axis 4.

The head portion 12 includes two sets of movable beam defining jaws, asof lead, which are movable to define the length L and thickness; T ofthe field of the X-ray beam as collimated by the beam defining jaws. Thesource 12 is enclosed in a barrel shaped collimator housing 15. Thesource housing 15, along with beam defining jaws, are rotatable aboutthe beam axis 13. The gantry 8 includes a beam stopping portion 16disposed along the X-ray beam axis 13 and holding an X-ray absorbingmaterial, such as lead, for stopping and absorbing the X-ray beam.

A digital computer 18, such as a Varian Data Machine Model 620/i generalpurpose digital computer, is coupled to the radiation therapy machine 1via the intermediary of a control cable 19 and an interface 21. Thecomputer 18 includes a core memory portion 22 interconnected to acentral processor 23 which includes the address and arithmetic units.Sixteen channels of analog-to-digital converters 24 are provided forconverting analog output signals derived from the radiation therapymachine 1 to digital form which are in turn fed into the centralprocessor 23 for use therein and for use in the memory 22. Eightchannels of digitalto-analog converters 25 are provided for convertingdigital output signals from the central processor 23 into analog signalswhich in turn are fed into the radiation therapy machine 1 via theintermediary of the interface 21. Sensor and control lines 26 areprovided for sensing and controlling functions of the radiation therapymachine via the interface 21. A machine console 27 is coupled to theradiation therapy machine 1 and to the computer 18 via the machineinterface 21.

The Varian data machines 620/i computer 18 is a system oriented digitalcomputer. It has a total memory capacity of 12,388 words of 16 or 18bits and is plug-in expandable. The memory is magnetic core with 1.8microseconds full cycle and 700 nanoseconds access time. The arithmeticis parallel, binary, fixed points, 2s complement. It has sevenaddressing modes and over one hundred standard instructions. Inaddition, to the standard equipment which comes with the Varian 620/icomputer, the computer 18 includes, a 620/i expansion chassis, two 620/imemory modules providing an extra 8,192 words, a 620/i-17 optionalpackage, a 620/i-l paper tape reader, an acquisition and control unit,and the 620/i machine interface 21.

The 620/i-l7 optional package contains hardware multiply/divide,extended addressing, real time clock, power fail/restart, and eightlevel priority interrupts. The 620/i-51 accessory is a high speed papertape reader which provides for rapid means to load the memory should aprogram be lost or scrambled for some reason. It is an input device onlyand will not punch. It reads at 300 characters per second.Theacquisitionand control unit contains the following: 7 or 12 bits plus signprogrammable sample-and-hold, 16 channels or multiplexedanalog-to-digital conversion 24, and the eight channels of 9 bit plussign digitaltoanalog converters 25 plus 16 sense and eight control lines26. In addition, the acquisition and control unit contains the BCDregisters and controller for the BCD information available from theradiation machine 1.

A digital cassette tape unit 28, such as a model 100 COMPUCORDERavailable from Datatronics, Inc. of Rochester, New York, is coupled bysuitable cables to the central processor 23 for reading digital data,stored in the patients individual cassette, into the central processor23 and memory 22. In addition, outputs from the processor 23 arerecorded back into thepatients cassette via the tape unit 28. A cathoderay tube/keyboard terminal 29, such as a model ALPHA 103A CRT/keyboardterminal, commercially available from Beehive Medical Electronics, Inc.of Salt Lake City, is coupled to the central processor 23 via cable 31for displaying data read from the memory 22 through the centralprocessor 23 and for controlling certain operations of the radiationtherapy machine 1 via the computer 18.

The CRT terminal 29 forms the major input-output device for the computer18 and includes an alpha numeric display. It has a standard typewriterkeyboard and four way cursor control. In addition, it has an 1 1 inchCRT screen with 20 lines and 40 characters per line. The CRT terminal 29has type-over capability using the cursor as well as line-erase andscreen-clear. It has its own internal character generator with 64characters ASC Il set. A remote slave cathode ray tube (CRT) 32 isprovided for remote data observation. A standard ASR 33 teletype unit iscoupled to the central processor 23 via suitable cables to provide ahard copy printout and to serve as a backup input for the CRT/keyboardterminal 29 and for the paper tape reader accessory of the computer 18.

Referring now to FIG. 2 there is shown one of the circuits forgenerating an analog positional signal determinative of the position ofone of the variable parameters of the radiation machine 1, such as:gantry angle G; housing angle, H; couch position in the X, Y and Zdirections, etc. The positional signal circuit of FIG. 2 includes apotentiometer 34, as of 10 k ohms, attached to the drive shaft 35 viamechanical coupling 36. Drive shaft 34 generates the motion of theparameter being controlled, such that a full-scale motion of theparameter being varied or controlled results in generating a full scale+10 volts to -10 volts analog output derived from the pickoff 37 of thepotentiometer 34. IS volts and +15 volts, respectively, are applied toopposite ends of the potentiometer 34 through trimming potentiometers 38and 39 provided at the ends of the potentiometer 34. The trimmingpotentiometers 38 and 39 provide for calibration of the range and theend points for each positional output readout. One turn 0.25 percentlinearity, 0.095 percent resolution potentiometers 34 are utilized onthe beam collimator jaws, and position indicators. Ten turn 0.1 percentlinearity, 0.019 percent resolution potentiometers 34 are provided foreach of the other analog positional readouts.

Each of the motorized control motions of the radiation machine 1 isdriven by a shunt-wound dc motor 40 operated by an SCR controller 41.With exception of the gantry rotation controller, each controller isopenloop providing full output in response to a 6-volt dc signal,decreasing to 0 output at 0.5 volts dc (10.5 dead band volts). Thegantry speed control is closed loop, speed regulated, full speed outputin response to a 12- volt dc input, against with 10.5 dead band volts.The turntable drive is equipped with a brake which is engaged when theinput voltage of the motor controller is zero. The couch longitudinaland lateral motions have switch actuated electric clutches engagingtheir respective drives.

Control of each motion of the radiation therapy machine l is obtained bydirect digital control. Positions of each of the eight analog motionsare sampled, by sampling the output of each potentiometer 34, every 50milliseconds, l0 microseconds required for each sample. Sampling iscontrolled by the central processor 23 and is effected through theinterface 21 to the positional control circuits of FIG. 2 coupled to thedrive 35 for each of the driven elements of the radiation therapymachine 1. The driven motions are sufficiently fast so as to alter theirfeedback from zero to full scale in seconds. Assuming a 12-bit plus signanalog-tvdigital converter output will vary a maximum of oneleastsignificant bit in 3.6 milliseconds, allowing observation of atmost four least-significant bit changes at every reading.

Each patient has in his file a digital tape cassette. For treatment of apatient, his cassette is loaded into the tape unit 28 and a command fromthe keyboard termi nal 29 causes the tape to be read into the centralprocessor 23and stored in the memory 22 of the computer 18. Theinformation transferred from the cassette to the memory 22 of thecomputer 18 includes the patients identification number, his name, thediagnosis of his condition, the portal definition of eight separateradiation treatment portals, each including an identification number 1-8and a definition of the quantities, G, 8,, X, Y, Z, H, L, T, and dosefor each of the defined portals, whether the individual treatment willinvolve arc therapy, and if so the start and stop gantry angles G, andthe rads per degree, and information as to which, if any wedge is to beemployed and whether blocks are to be employed. Wedges serve to shapethe intensity of the radiation beam, and blocks serve to protect certainportionsof the patient being treated for radiation emanating from thebeam. In addition, information stored in the memory 22 from the patientscassette, includes a sequence of how the portal definitions are to beadministered, i.e., the treatment plan, the monitored cumulative doseper portal, and the total cumulative dose for the patient.

Once this information has been stored in the computer 18, the keyboardterminal 29 is actuated for displaying desired information from thememory 22 on the display of the keyboard terminal 29. On a propercommand from the keyboard terminal 29, the central processor 23 causesto be displayed, from the memory 22, on the cathode ray tube display 29,the next treatment to be given. For example, a certain radiation portalis defined on the visual alphanumeric CRT display, with the prescribed"set points for the quantities of G,S,X,Y,Z,H,L,T, etc. Opposite theprescribed values for the aforementioned quantities, which define thetreatment to begiven, is displayed the corresponding present position ofeach of the settings of the radiation therapy machine 1. Positionalvalues are obtained from the output of the positional circuits of thetype shown in FIGL 2 as converted to digital form via theanalog-todigital converters 24 and as sent to the display tube of thekeyboard terminal 29, from the central processor 23; Upon depressing theproper command button on the machine control pendant 10, the centralprocessor 23 causes the actual positional'signal to be monitored and tobe compared with the prescribed positional signal to derive errorsignals which are fed to the controllers for causing the radiationtherapy machine 1 to take the positions defined by the treatment planbeing exe cuted.

An anti-collision program is stored in the memory 22 and the centralprocessor, in conformance with the program, continually checks for thepossiblity of a collision between the gantry 8 and the couch 2. Ifimminent collision is determined, an anti-collision subroutine isexecuted to avert the collision. The radiation machine is positioned inaccordance with the predetermined prescribed plan. The geometric setpoints can be achieved in less than 30 seconds because all of thegeometric motions of the radiation machine are obtained simultaneously.

As each of the geometric parameters achieves its set point, the setpoint value is displayed on the cathode ray tube opposite thecorresponding prescribed value for the treatment plan being executed.Thus, all the set point valuesfor the quantities G, S, X, Y, Z, H, L andT are achievedautomatically and presented automati cally. The plannedvalues for dose,time, rads per degree, stop angle, wedge and blocks aredisplayed but these adjustments are made manually from the machineconsole 27. Each of the manual adjustments from the machine console 27has a BCD positional output signal generator of conventional designcoupled thereto in the conventional manner. As the manually adjustableparameters are set, the: corresponding positional value. is fed into thecomputer 18 and presented on the display adjacent the planned value.Each wedge and block is separately coded with electrical connections andelectrical connections are made to these coded connections for feedingan input signal to the computer 18 corresponding to the particular wedgeor block employed. Thus wedge and block information is also fed to thecomputer and presented on the display 29.

The computer 18 is programmed to compare the prescribed value for all ofthe aforementioned geometric and other machine parameters against theset point values achieved for each of the adjustable parameters. If allof the prescribed values do not conform to the set point values, thecomputer 18 generates an interlock output signal which is fed via themachine interface 21 to actuate a relay 45 which opens a circuit in themachine console 27 and prevents energizationof the radiation ON" button46 in the machine console 27 such that the beam of radiation cannot beturned onto the patient until. all of the actual set points values forthe variable parameters of the radiation machine conform to theprescribed values. This greatly reduces the probability of the operatormaking a mistake and delivering a dose of radiation to the patient whichis not called for by the prescribed treatment plan. Tolerances in themechanical settings can be built into the system to com-- pensate foruncertainties in patient positioning on the treatment couch 2.

The radiation head portion 12 of the radiation therapy machine 1includes a dosimeter 20 for monitoring the dose of radiation actuallyadministered to the patient. The output from the dosimeter iscontinually monitored by the computer 18 throughout the treatment. Themeasured radiation dose per treatment is stored in the memory 22 of thecomputer and displayed on the CRT/terminal display 29. In addition, thecomputer updates the patient treatment plan status information stored inthe memory 22 by updating the portal status portion of the treatmentplan to include the eumulative total of radiation dose administeredthrough the particular portal just administered and the total doseadministered to the patient. The status information is also updated toinclude which treatments in the sequence of treatments has beenadministered and which numbered treatment is to be administered next.

The treatment plan portion of the patients treatment plan informationstored in the memory 22 is also updated by the computer by entering amark such as an asterisk under the number of the portal definition justadministered in the sequence of portal numbers which defines thetreatment plan sequence.

After the treatment is terminated an interlock signal goes to thecomputer 18 from the radiation machine 1. This interlock signal preventsthe computer from performing any functions other than printing out theupdated portal definition information for the portal just administered.The print out is on the teletype 33. The print out includes the completeportal definition of prescribed and present positions of the elements,etc., together with present date, time, cumulative dose for this portaland the grand total of dose administered to the patient.

After the print out, the operator types the command END at the keyboardterminal which commands the computer 18 to readout all the updatedtreatment plan information, portal definition information, etc.,relating to this patient from the memory 22 back into the individualpatients tape cassette via the tape deck unit 28.

Any detail of the prescribed overall radiation treatment plan or any oneof the prescribed parameters of an individual portal descriptions can beeasily changed during the course of treatments. The operator pushes anEDIT button on the CRT keyboard terminal 29 and types in the appropriatechange at the keyboard. Two levels of edit capability are incorporated.Certain major changes, such as overall treatment plan, can only beinitiated by supervisory personnel with a special access key whichserves to complete an interlock circuit in an interface between theCRT/keyboard terminal 29 and the central processor 23. If the therapistdesires periodic examination before certain treatments can beadministered to the patient, he can require that some one of supervisoryrank be present at a given treatment by typing in an appropriate legendin the overall treatment plan.

Any proposed new machine parameter for a change in a treatment plan orportal definition is compared by the computer 18 against the respectivepermissible ranges for that parameter stored in the memory 22. If theproposed value of the parameter is within the permissible range thechange is entered and the treatment plan. or portal definition stored inthe memory 22 is thus edited.

If the proposed change in parameter is not within the permissible rangeof values, an error message is displayed on the CRT display 29 and theproposed parameter change is not entered.

The computer assisted radiation machine 1 also in cludes a simulatormode of operation. In the simulator mode the radiation therapy machineis manually controlled by the operator from the pendant 10 to positionthe geometric machine parameters for a certain treatment to beadministered. The final settings of the machine are monitored by therespective positional output signals and define portions of a completeportal definition. Upon a command the operator causes the computer 18 totransfer the manually set machine parameters into the memory 22 toestablish a portal definition in a treatment plan of information storedfor that patient in the memory 22. Subsequently this portal definitionis completed by the operator and becomes a part of the patient treatmentplan to be transferred to his cassette in the manner as previouslydescribed above. A computer program flow chart the aforedescribedcomputer program is shown in FIG. 3.

Since many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

RELATED CASES The simultaneous motion and anti-collision program aredescribed and claimed in copending U.S. application Ser. No. 93,327filed Nov. 27, 1970, now U.S. Pat. No. 3,720,817. The feature ofverifying the prescribed treatment plan against the actual settings ofthe radiation machine is disclosed and claimed in copending U.S.application Ser. No. 93,332 filed Nov. 27, 1970, both applications areassigned to the same assignee as the present invention.

What is claimed is:

1. In a radiation therapy apparatus, couch means for supporting apatient to receive radiation, radiation source meansfor applyingradiation to the patient, means for supporting and moving said radiationsource means around said couch means, means for storing informationdefining geometric and radiation dose parameters of the radiationmachine for defining a prescribed radiation treatment to be administeredto the patient, means for reading out of said storage means anddisplaying to an operator the geometric and dose parameters defining theprescribed plan of radiation treatment, means for deriving an outputrepresentative of the dose of radiation actually administered to thepatient from said source means in carrying out the defined plan oftreatment, means for automatically editing and updating said storagemeans with the derived dose output by adding the derived dose output tothe cumulative total of previously derived dose outputs, if any,administered to the patient and stored in said storage means, to obtainan updated cumulative total radiation dose output in said storage means.

2. The apparatus of claim 1 wherein said means for displaying andreading out of said storage means the parameters of a prescribed plan oftreatment includes, means for reading out the edited and updatedcumulative total radiation dose output from said edited and updatedstorage means.

3. The apparatus of claim 1 wherein said storage means and said editingand updating means includes, a programmed general purpose computer.

4. The apparatus of claim 3 wherein said readout and display meansincludes, cathode ray tube terminal means interactively coupled to saidgeneral purpose computer means.

5. The apparatus of claim 3 wherein said readout and display meansincludes, teletype terminal means interactively coupled to saidprogrammed general purpose computer means for printing out the editedand updated treatment plan parameter stored in said storage means.

6. The apparatus of claim 1 wherein said means for deriving an outputrepresentative of the dose of radiation actually administered to thepatient includes, dosimeter means disposed in the beam of radiationadministered to the patient.

7. The apparatus of claim 1 including, programmed general purposecomputer means having a memory portion, and wherein said storage meansfor storing the geometric and dose parameter information defining aprescribed radiation treatment plan includes said mem ory of saidcomputer means, and including second information storage means forstoring geometric and dose parameter information defining a prescribedradi ation treatment plan for a given patient, means for reading thetreatment plan information stored in said second storage means into saidmemory portion of said computer means, means for recording informationin said second information storage means, and said computer means beingprogrammed to read the edited and updated treatment plan informationfrom said memory portion of said computer to said recording means forrecording the updated treatment plan information in said secondinformation storage means.

8. The apparatus of claim 7 wherein said second storage means includes,an information storage tape medium.

9. The apparatus of claim 1 wherein, said storage means also includesmeans for storing information defining permissible ranges of values oftreatment plan parameters for radiation treatment plans to beadministered to the patient, means for comparing a proposed radiationtreatment plan parameter against the respective parameter of the rangeof permissible values to'derive an interlock output if the valve of theproposed machine parameter is outside the respective range ofpermissible parameter values, and means responsive to the interlockoutput to prevent transfer of the out-ofrange proposed machine parameterinto the prescribed set of treatment plan parameters stored in saidstorage means.

1. In a radiation therapy apparatus, couch means for supporting apatient to receive radiation, radiation source means for applyingradiation to the patient, means for supporting and moving said radiationsource means around said couch means, means for storing informationdefining geometric and radiation dose parameters of the radiationmachine for defining a prescribed radiation treatment to be administeredto the patient, means for reading out of said storage means anddisplaying to an operator the geometric and dose parameters defining theprescribed plan of radiation treatment, means for deriving an outputrepresentative of the dose of radiation actually administered to thepatient from said source means in carrying out the defined plan oftreatment, means for automatically editing and updating said storagemeans with the derived dose output by adding the derived dose output tothe cumulative total of previously derived dose outputs, if any,administered to the patient and stored in said storage means, to obtainan updated cumulative total radiation dose output in said storage means.2. The apparatus of claim 1 wherein said means for displaying andreading out of said storage means the parameters of a prescribed plan oftreatment includes, means for reading out the edited and updatedcumulative total radiation dose output from said edited and updatedstorage means.
 3. The apparatus of claim 1 wherein said storage meansand said editing and updating means includes, a programmed generalpurpose computer.
 4. The apparatus of claim 3 wherein said readout anddisplay means includes, cathode ray tube terminal means interactivelycoupled to said general purpose computer means.
 5. The apparatus ofclaim 3 wherein said readout and display means includes, teletypeterminal means interactively coupled to said programmed general purposecomputer means for printing out the edited and updated treatment planparameter stored in said storage means.
 6. The apparatus of claim 1wherein said means for deriving an output representative of the dose ofradiation actually administered to the patient includes, dosimeter meansdisposed in the beam of radiation administered to the patient.
 7. Theapparatus of claim 1 including, programmed general purpose computermeans having a memory portion, and wherein said storage means forstoring the geometric and dose parameter information defining aprescribed radiation treatment plan includes said memory of saidcomputer means, and including second information storage means forstoring geometric and dose parameter information defining a prescribedradiation treatment plan for a given patient, means for reading thetreatment plan information stored in said second storage means into saidmemory portion of said computer means, means for recording informationin said second information storage means, and said computer means beingprogrammed to read the edited and updated treatment plan informationfrom said memory portion of said computer to said recording means forrecording the updated treatment plan information in said secondinformation storage means.
 8. The apparatus of claim 7 wherein saidsecond storage means includes, an information storage tape medium. 9.The apparatus of claim 1 wherein, said storage means also includes meansfor storing information defining permissible ranges of values oftreatment plan parameters for radiation treatment plans to beadministered to the patient, means for comparing a proposed radiationtreatment plan parameter against the respective parameter of the rangeof permissible values to derive an interlock output if the valve of theproposed machine parameter is outside the respective range ofpermissible parameter values, and means responsive to the interlockoutput to prevent transfer of the out-of-range proposed machineparameter into the prescribed set of treatment plan parameters stored insaid storage means.